The invention relates to a method for determining the behavior of shafts of a multi-shaft machine which are jointly movable to move a tool or a tool receptacle. For example, drilling or milling can be carried out with the aid of such a multi-shaft machine. The coordinated movements of the various machine shafts serve for moving a drill/milling cutter on a curve in space, in order thereby to generate specific contours on a workpiece.
It is known to characterize the behavior of the individual shafts individually. In addition to the individual behavior of the shafts, however, it is usually desirable to be able to have evidence of the interaction of the shafts. Specific tests have been developed for this purpose.
A test in very widespread use is what is known as the circularity test. In a circularity test, two shafts are moved in coordination with one another, so that the tool (its tip) or the tool receptacle ideally moves on a circular path contour. The deviation of the real path from this circularity is useful for analyzing the behavior of the two shafts. For this purpose, the positions during travel along the path are measured, special measuring instruments and evaluation programs being employed in the circularity test. A two-dimensional illustration of the path in comparison with a circle is thus obtained. Characterizing quantities, such as what is known as the circularity deviation and the circle reversal span, can be derived.
Other tests for determining the behavior of the jointly movable machine shafts have in common with the circularity test the fact that, in real terms, at least two selected machine shafts are moved, and that the tool or tool receptacle follows a path which is detected and is compared with a desired path. Paths of the most diverse possible kinds which are different from a circle are defined in this way.
It has been difficult to conduct previous tests because the shafts must, in real terms, execute a specific coordinated movement which has to be programmed specifically. It is not always possible that a specific machine actually generates the desired contour, such as, for example, the circular contour. Measuring the positions of the tool or of the tool receptacle is highly complicated.